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排序方式: 共有102条查询结果,搜索用时 312 毫秒
1.
Phillips CJ Foster CR Morris PA Teverson R 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2002,3(1):3-13
Genetic variation in the susceptibility of cattle to Mycobacterium bovis infection exists in differences between families and species, but not breeds. Susceptibility to M. bovis infection increases with age of cattle. Natural exposure to M. bovis or environmental mycobacteria may assist in the development of specific immunity, but there is no direct evidence for such immunological priming of tuberculosis resistance in cattle. This has, however, been demonstrated in humans and other animals. Since non-specific mechanisms have a role in protective immunity, developing an effective vaccine will be difficult, even though some protection of other species has been achieved. Immunological suppression in the periparturient period can produce anergic reactors, which may act as a constant source of infection for cattle-to-cattle transmission. Circumstantial evidence suggests that an adequate intake of mineral, vitamin and protein reduces the susceptibility of cattle. Although weather patterns have been implicated in the susceptibility of herds to M. bovis infection, there is insufficient information to determine the risk factors precisely. It is concluded that some reduction in the susceptibility of cattle to M. bovis infection can be achieved by modifications to the management system to minimize risk factors, but that a considerable amount of further research is required. 相似文献
2.
Application and field validation of a PCR assay for the detection of Mycoplasma hyopneumoniae from swine lung tissue samples. 总被引:1,自引:0,他引:1
Hugh Y Cai Tony van Dreumel Beverly McEwen Geoff Hornby Patricia Bell-Rogers Pat McRaild Gaylan Josephson Grant Maxie 《Journal of veterinary diagnostic investigation》2007,19(1):91-95
A PCR assay was validated for the detection of Mycoplasma hyopneumoniae in porcine lung tissue. The detection limit of the assay was 0.18 colony-forming units/g of lung sample spiked with M. hyopneumoniae. In field validation, 426 pigs from 220 cases were examined for M. hyopneumoniae infection by M. hyopneumoniae PCR and a fluorescent antibody (FA) test. In total, 103 pig lungs (24.2%) were positive in the PCR test, and 69 pig lungs (16.2%) were positive in the FA test, among which, 62 pigs were positive for both PCR and FA test. Most of the PCR-positive but FA test-negative cases had lesions compatible with M. hyopneumoniae infection. With Bayesian modeling, the diagnostic sensitivity and specificity of the PCR were determined to be 97.3% and 93.0%, respectively. 相似文献
3.
Mannheimia granulomatis PCR检测方法的建立 总被引:3,自引:0,他引:3
Mannheimia granulomatis是导致牛、羊呼吸道传染病的一种病原菌.为快速、准确诊断由该菌导致的疫病,从基因库中获得M.granulomdtis的基因序列,再从M.granulomatis的基因序列中获得与其他细菌包括溶血性曼氏杆菌和多杀性巴氏杆菌等不同的基因片段,设计引物,建立了特异性好、敏感性较高的M.granulomatis的PCR诊断方法.结果表明,其特异性为100%,最小检出量为5×104cfu/mL~5×103cfu/mL M.granulomatis或1/10个单个菌落. 相似文献
4.
The herbicide, hexazinone, was applied four ways over ponderosa pine, 2–0 seedlings planted in northeast Oregon. The four treatments were two broadcast applications, a single broadcast application, a large spot application, and a small spot application. Seedling survival and growth were monitored for five growing seasons. Results indicate that survival more than doubled with either large or small spot applications compared to no application, and either one or two broadcast applications can increase survival an additional 30% over spot applications. Differences in stem volume were substantial, with two broadcast applications yielding more than twice the volume of a single broadcast treatment and more than five times the volume of seedlings treated with spot applications. Trees in small spots were still three times bigger than surviving seedlings in the control. These results are consistent with the concept of competition threshold. Management implications were considered in terms of cost of established seedlings. Although broadcast applications cost more per acre than spot applications, gains in seedling survival, growth and quality offset the additional cost and translate into lower established seedling costs. The cost effectiveness of broadcast applications also may be seen in the elimination of replanting or in-planting requirements and increases in long-term growth potential of the established trees. 相似文献
5.
Wrieden WL Anderson AS Longbottom PJ Valentine K Stead M Caraher M Lang T Gray B Dowler E 《Public health nutrition》2007,10(2):203-211
OBJECTIVE: To evaluate the feasibility of undertaking a food skills intervention study in areas of social deprivation aimed at altering cooking confidence, food preparation methods and dietary choices. DESIGN: A standardised skills programme was implemented in community-based settings. Pre- (T1) and post-intervention (T2) and 6-month follow-up (T3) measures (7-day diaries and self-administered questionnaires) were undertaken in intervention and comparison groups. SETTING: Eight urban communities in Scotland. SUBJECTS: One hundred and thirteen adults living in areas of social deprivation. RESULTS: It was clear that many subjects led fragmented lives and found commitment to intervention classes problematic. Sixty-three subjects completed the final (T3) assessments. The response to each component varied due to inability to attend sessions, illness, study requirements, employment, moving out of the area, change in circumstances, loss of interest and loss of postal questionnaires. At baseline, reported consumption of fruit and vegetables was low (mean frequency 8.1 +/- 4.78 times per week). Fruit intake increased significantly (P < 0.05) between T1 and T2 in the intervention group (1.7 +/- 2.36 to 2.7 +/- 3.28 times per week) only. Between T1 and T3, there was a significant increase (P < 0.05) in intervention subjects who reported confidence in following a recipe (67-90%,). CONCLUSIONS: This exploratory trial shows that a food skills intervention is likely to have a small but positive effect on food choice and confidence in food preparation. A full-scale randomised controlled trial in this hard-to-reach group would require a range of flexible approaches rather than a fully defined intervention, and presents challenges for trial design. 相似文献
6.
7.
Ashalatha?S.?Nair Chee?How?Teo Trude?Schwarzacher Pat?Heslop?HarrisonEmail author 《Euphytica》2005,143(3):285-290
Summary The banana cultivars are originated from the intra- and inter-specific hybridization of two wild diploid species, Musa acuminata Colla and Musa balbisiana Colla, contributing the A and B genomes, respectively. They are classified into genomic groups by scoring morphological features.
Molecular markers provide a quick and reliable system of genome characterization and manipulation in breeding lines. In the
present study a PCR based molecular marker specific for B genomes is been reported. The IRAP primer, designed based on the
LTR sequence of banana Ty3-gypsy-like retroelement (Musa acuminata Monkey retrotransposon, AF 143332), was used to identify the B genome in the banana cultivars. Further a primer pair designed
from B specific bands of Musa balbisiana `Pisang Gala' was used to classify AAB and ABB cultivars in the collection. Among the 36 cultivars tested with this primer,
the B specific band was absent in the AA and AAA cultivars (except in one AAA and AAB cultivar) but present in all other AB,
AAB and ABB cultivars. Among the triploid AAB/ABB, the PCR products with B specific primers showed restriction pattern polymorphism
with AluI. In ABB genomes the band intensity was high whereas low intensity band observed in AAB genomes. Four cultivars reported
to have the ABB genome showed a pattern similar to AAB, and one cultivar reported to have AAA genome showed a pattern similar
to ABB genome, suggesting missampling or misidentification. The primers used in this study are useful to identify the presence
of B genome in banana cultivars, and band intensity may be a preliminary indicator of ploidy level of the B genome but needs
further studies with competitive PCR for clarification.
These authors contributed equally in this paper. 相似文献
8.
Over four hundred vegetation samples were collected for total Hg determination as part of a biogeochemical survey in the Precambrian
Shield region near Huntsville, Ontario. An objective of the survey was to obtain accurate data describing the spatial and
temporal variation of Hg concentrations in vegetation. Five tree species, clubmosses, mosses, lichen and fungi were collected
along three transects each 8 to 10 km long. The samples were digested using a hot H2SO4/HNO3 mixture followed by cold-vapor AAS detection. Very low detection limits (less than 1.0 ng g−1) were achieved by performing the analyses in a clean, Hg-free laboratory. The Hg concentration of coniferous needles did
not vary significantly over eight weeks of the summer, but did vary significantly between first and second year growth. In
all tree species examined, Hg concentrations in needles/leaves were two to three times as high (by dry weight) as that in
twig tissue from the same branch. Differences in Hg content between tissues of different types and ages constituted a major
source of within-site variation between plants of the same species. 相似文献
9.
Survival ofEscherichia coli was studied in water from the Great Salt Lake, a highly saline lake with an ionic composition much like sea water. Samples used were from the most concentrated north arm (343.1 g l?1 solids) and the less concentrated south arm (about 113 g l?1 solids). At temperatures from 20°C to 9°C the bacterial death rate (k) for the north arm was ?0.17 log day?1 and the south arm and 1:3 dilution ?0.28 log day?1. Above 9°C the rate of death increased approximately exponentially and at 19°C the rate of death increased approximately exponentially and at 19°C the death rate was ?1.31 log day?1 in the north arm and ?0.98 log day?1 in the lower salinity water. These rates fall within those reported for sea water and are much higher than fresh water. Possible causes of death are discussed with the most likely being the high concentrations of minor elements or osmotic stress. The survival characteristics ofE. coli in waters with a sea water-like composition should require the same health concern as sea water regardless of the actual concentration of salt. High salt water of other ionic composition may behave differently, however. 相似文献
10.